[2/3] fuse: ignore 'data' argument of mount(..., MS_REMOUNT)
diff mbox series

Message ID 20200710115805.4478-2-mszeredi@redhat.com
State New
Headers show
Series
  • [1/3] fuse: use ->reconfigure() instead of ->remount_fs()
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Commit Message

Miklos Szeredi July 10, 2020, 11:58 a.m. UTC
The command

  mount -o remount -o unknownoption /mnt/fuse

succeeds on kernel versions prior to v5.4 and fails on kernel version at or
after.  This is because fuse_parse_param() rejects any unrecognised options
in case of FS_CONTEXT_FOR_RECONFIGURE, just as for FS_CONTEXT_FOR_MOUNT.

This causes a regression in case the fuse filesystem is in fstab, since
remount sends all options found there to the kernel; even ones that are
meant for the initial mount and are consumed by the userspace fuse server.

Fix this by ignoring mount options, just as fuse_remount_fs() did prior to
the conversion to the new API.

Reported-by: Stefan Priebe <s.priebe@profihost.ag>
Fixes: c30da2e981a7 ("fuse: convert to use the new mount API")
Cc: <stable@vger.kernel.org> # v5.4
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/fuse/inode.c | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

Sasha Levin July 16, 2020, 12:27 a.m. UTC | #1
Hi

[This is an automated email]

This commit has been processed because it contains a "Fixes:" tag
fixing commit: c30da2e981a7 ("fuse: convert to use the new mount API").

The bot has tested the following trees: v5.7.8, v5.4.51.

v5.7.8: Build OK!
v5.4.51: Failed to apply! Possible dependencies:
    7f5d38141e309 ("new primitive: __fs_parse()")
    82995cc6c5ae4 ("libceph, rbd, ceph: convert to use the new mount API")
    d7167b149943e ("fs_parse: fold fs_parameter_desc/fs_parameter_spec")


NOTE: The patch will not be queued to stable trees until it is upstream.

How should we proceed with this patch?
Miklos Szeredi July 20, 2020, 9:14 a.m. UTC | #2
On Thu, Jul 16, 2020 at 2:27 AM Sasha Levin <sashal@kernel.org> wrote:
>
> Hi
>
> [This is an automated email]
>
> This commit has been processed because it contains a "Fixes:" tag
> fixing commit: c30da2e981a7 ("fuse: convert to use the new mount API").
>
> The bot has tested the following trees: v5.7.8, v5.4.51.
>
> v5.7.8: Build OK!
> v5.4.51: Failed to apply! Possible dependencies:
>     7f5d38141e309 ("new primitive: __fs_parse()")
>     82995cc6c5ae4 ("libceph, rbd, ceph: convert to use the new mount API")
>     d7167b149943e ("fs_parse: fold fs_parameter_desc/fs_parameter_spec")
>
>
> NOTE: The patch will not be queued to stable trees until it is upstream.
>
> How should we proceed with this patch?

Conflict resolution is trivial.

Thanks,
Miklos

Patch
diff mbox series

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index be39dff57c28..ba201bf5ffad 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -477,6 +477,13 @@  static int fuse_parse_param(struct fs_context *fc, struct fs_parameter *param)
 	struct fuse_fs_context *ctx = fc->fs_private;
 	int opt;
 
+	/*
+	 * Ignore options coming from mount(MS_REMOUNT) for backward
+	 * compatibility.
+	 */
+	if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE)
+		return 0;
+
 	opt = fs_parse(fc, fuse_fs_parameters, param, &result);
 	if (opt < 0)
 		return opt;